A systematic review summarizes the results of a number of individual studies that address a focused clinical question. It may be accompanied by a meta-analysis, which is a quantitative method of combining the results of all these studies in order to come up with a summary statistic of the overall effect of an intervention. Single studies may be unrepresentative of the total body of evidence, that is why combining the results of several studies in a systematic review increases precision, provides better estimates of effect, and includes a greater range of patients thus facilitating better clinical decision making. This must be done in a systematic and reproducible manner.
Systematic Review ; Meta-Analysis